The mechanisms by which the wiring of the central nervous system is established during development are an important topic of basic neuroscience. Although much attention has been paid to the mechanisms of axon guidance, there are major gaps in our understanding of the processes used by dendrites to establish specific synaptic connections. This project uses the tractable Drosophila embryonic nervous system to tease apart the mechanisms of dendritic guidance. The previous and preliminary results show unexpected and novel aspects of this process that are very likely to have an important impact on how we think about molecules involved in pathfinding. Although previously identified molecules are being studied, the evidence so far obtained makes a clear case that the same molecules work in different ways in specific neurites within the same neuron, and that different identified neurons may use the same set of molecules in different ways. A set of integrated hypotheses, each of which can be adapted to general situations, will be tested by this project. If successful, outcome of this project will provide a much-needed background to understanding the cause of diseases that affect brain connectivity.